Mechanically deployable beds have been in existence for many years for temporary sleeping accommodations and for regular use in limited space. In many cases such beds take the form of convertible sofas or chairs which have a mattress folded therein or in which the cushions can be folded out to form a mattress. Other types of folding beds include well known rollaway beds which can be folded up and rolled to a place of storage and Murphy-type beds which fold into closet-like enclosures. Still other types of beds combine various types of furniture with a bed. For example, one known unit includes a chest of drawers, a mirror, a couch, and a trundle bed-type slidable mattress frame.
In an effort to facilitate the conversion of combination beds and the deployment of folding beds, attempts have been made to employ motors such as electric motors. In general, there have been problems in devising motorized convertible or deployable beds of practical sizes and weights and at an acceptable price. Convertible and deployable beds tend to be large and heavy, and the addition of a motor and motion transfer elements add to the weight. In addition, there have been reliability problems, particularly where cables are used to transfer motion from the motor to the movable bed portions due to the complexity of the mechanism and the tendency of cables to stretch.
In one known bed arrangement, (U.S. Pat. No. 4,449,263 to Wilson, et al.), the deployment mechanism is a pivoted jackscrew device such as are used on adjustable type hospital beds. The screw device is connected to a lever at an extreme end of the rigid mattress frame. Because of a leverage disadvantage, at least one counterbalancing mechanism is needed to help raise the frame for storage. Since the frame is pivoted from the end, the deployment mechanism must be extra rugged to prevent failure thereof which could be a very hazardous situation.
In another known arrangement (U.S. Pat. No. 3,417,397 to Moore), the deployment mechanism includes a fixed position motor and elongated screw shaft assembly and a nut member which is pivotally connected to the mattress frame. The rigid mattress frame is lifted by a proximal end while the distal end follows on casters. Both the Moore and Wilson et al. devices are relatively complex mechanisms which increases the cost of their manufacture and installation.
In many deployable bed arrangements, the mattress frame is stored and extended in a lengthwise direction. Such lengthwise deployment increases the intrusion of the mattress frame into the room in which it is situated thus limiting the flexibility of furniture placement near the bed.